Clinical outcomes of transcarotid artery revascularization vs carotid endarterectomy from a large single-center experience.

BACKGROUND: Transcarotid artery revascularization (TCAR) has been practiced as an alternative for both carotid endarterectomy (CEA) and transfemoral carotid artery stenting, specifically in high-risk patients. More recently, the Centers for Medicare and Medicaid Services expanded coverage for TCAR in standard surgical risk patients if done within the Society for Vascular Surgery Vascular Quality Initiative TCAR surveillance project. A few registry studies (primarily from the Society for Vascular Surgery Vascular Quality Initiative) compared the early and up to 1-year outcomes of TCAR vs CEA or transfemoral carotid artery stenting. There is no large single-center study that reported late clinical outcomes. The present study compares intermediate clinical outcomes of TCAR vs CEA. METHODS: This study retrospectively analyzed collected data from TCAR surveillance project patients enrolled in our institution and compare it with CEA patients done by the same providers at the same time period. The primary outcome was combined perioperative stroke/death and late stroke/death. Secondary outcomes included combined stroke, death, and myocardial infarction, cranial nerve injury (CNI), and bleeding. Propensity matching was done to analyze outcome. Kaplan-Meier analysis was used to estimate freedom from stroke, stroke/death, and ≥50% and ≥80% restenosis. RESULTS: We analyzed 646 procedures (637 patients) (404 CEA, 242 TCAR). There was no significant difference in the indications for carotid intervention. However, TCAR patients had more high-risk criteria, including hypertension, coronary artery disease, congestive heart failure, and renal failure. There was no significant differences between CEA vs TCAR in 30-day perioperative stroke (1% vs 2%), stroke/death rate (1% vs 3%; P = .0849), or major hematomas (2% vs 2%). The rate of CNI was significantly different (5% for CEA vs 1% for TCAR; P = .0138). At late follow-up (2 years), the rate of stroke was 1% vs 4% (P = .0273), stroke/death 8% vs 15% (P = .008), ≥80 % restenosis 0.5% vs 3% (P = .0139) for CEA patients vs TCAR patients, respectively. After matching 242 CEAs and 242 TCARs, the perioperative stroke rate was 1% for CEA vs 2% for TCAR (P = .5037), the stroke/death rate was 2% vs 3% (P = .2423), and the CNI rate was 3% vs 1% (P = .127). At late follow-up, rates of stroke were 1% for CEA vs 4% for TCAR (P = .0615) and stroke/death were 8% vs 15% (P = .0345). The rate of ≥80% restenosis was 0.9% for CEA vs 3% for TCAR (P = .099). The rates of freedom from stroke at 6, 12, 18, and 24 months for CEA vs TCAR were 99%, 99%, 99%, and 99% vs 97%, 95%, 93% and 93%, respectively (P = .0806); stroke/death were 94%, 90%, 87%, and 86% vs 93%, 87%, 76%, and 75%, respectively (P = .0529); and ≥80% restenosis were 100%, 99%, 98%, and 98% vs 97%, 95%, 93%, and 93%, respectively (P = .1132). CONCLUSIONS: In a propensity-matched analysis, both CEA and TCAR have similar perioperative clinical outcomes. However, CEA was superior to TCAR for the rates of late stroke/death and had a somewhat lower rate of ≥80% restenosis at 2 years, but this difference was not statistically significant.

Long-term durability and clinical outcome of a prospective randomized trial comparing carotid endarterectomy with ACUSEAL polytetrafluoroethylene patching versus pericardial patching.

BACKGROUND: Several studies have shown the superiority of carotid endarterectomy (CEA) with patch closure over primary closure. However, no definite study has shown any significant differences in clinical outcome between various types of patches. Because more vascular surgeons have used pericardial patching recently, this study will analyze the late clinical outcome (≥10 years) of our previously reported prospective randomized trial comparing CEA with ACUSEAL (polytetrafluoroethylene) vs pericardial patching. METHODS: A total of 200 CEAs were randomized (1:1) to either Vascu-Guard pericardial patching or ACUSEAL patching. All patients had immediate duplex ultrasound imaging, which was repeated at 6 months and annually thereafter. Kaplan-Meier analysis was used to estimate rates of freedom from stroke, stroke-free survival, and rates of freedom from ≥50% and ≥80% restenosis. RESULTS: Overall demographic and clinical characteristics were somewhat similar with a mean follow-up of 80 months (range: 0-149 months). The rates of freedom from stroke were 97, 97, 97, 96, 93 for ACUSEAL vs 99, 98, 97, 97, 92 for pericardial patching (P = .1112) at 1, 2, 3, 5, and 10 years, respectively. Similarly, the rates of freedom from stroke/death were 94, 93, 90, 76, 50 for ACUSEAL vs 99, 96, 91, 78, 47 for pericardial patching (P = .8591). The rates of freedom from ≥50% restenosis were 98, 98, 96, 89, 79 for ACUSEAL vs 87, 83, 83, 81, 71 for pericardial patching (P = .0489). The rates of freedom from ≥80% restenosis were 99, 99, 99, 96, 85 for ACUSEAL vs 96, 96, 96, 93, 93 for pericardial patching (P = .9407). The overall survival rates were 95, 94, 91, 77, 51 for ACUSEAL vs 100, 98, 93, 79, 50 for pericardial patching (P = .9123). Other patch complications (eg, rupture, aneurysmal dilation, infection, etc) were similar. CONCLUSIONS: Both CEA with ACUSEAL (polytetrafluoroethylene) and pericardial patching are durable and have similar clinical outcomes at 10 years except that ACUSEAL patching has significantly better rates of freedom from ≥50% restenosis.

Modifications of Epitaxial Graphene on SiC for the Electrochemical Detection and Identification of Heavy Metal Salts in Seawater.

The electrochemical detection of heavy metal ions is reported using an inexpensive portable in-house built potentiostat and epitaxial graphene. Monolayer, hydrogen-intercalated quasi-freestanding bilayer, and multilayer epitaxial graphene were each tested as working electrodes before and after modification with an oxygen plasma etch to introduce oxygen chemical groups to the surface. The graphene samples were characterized using X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, and van der Pauw Hall measurements. Dose-response curves in seawater were evaluated with added trace levels of four heavy metal salts (CdCl2, CuSO4, HgCl2, and PbCl2), along with detection algorithms based on machine learning and library development for each form of graphene and its oxygen plasma modification. Oxygen plasma-modified, hydrogen-intercalated quasi-freestanding bilayer epitaxial graphene was found to perform best for correctly identifying heavy metals in seawater.

Multilayer Epitaxial Graphene on Silicon Carbide: A Stable Working Electrode for Seawater Samples Spiked with Environmental Contaminants.

The electrochemical response of multilayer epitaxial graphene electrodes on silicon carbide substrates was studied for use as an electrochemical sensor for seawater samples spiked with environmental contaminants using cyclic square wave voltammetry. Results indicate that these graphene working electrodes are more robust and have lower background current than either screen-printed carbon or edge-plane graphite in seawater. Identification algorithms developed using machine learning techniques are described for several heavy metals, herbicides, pesticides, and industrial compounds. Dose-response curves provide a basis for quantitative analysis.

Machine Learning Techniques for Chemical Identification Using Cyclic Square Wave Voltammetry.

Electroanalytical techniques are useful for detection and identification because the instrumentation is simple and can support a wide variety of assays. One example is cyclic square wave voltammetry (CSWV), a practical detection technique for different classes of compounds including explosives, herbicides/pesticides, industrial compounds, and heavy metals. A key barrier to the widespread application of CSWV for chemical identification is the necessity of a high performance, generalizable classification algorithm. Here, machine and deep learning models were developed for classifying samples based on voltammograms alone. The highest performing models were Long Short-Term Memory (LSTM) and Fully Convolutional Networks (FCNs), depending on the dataset against which performance was assessed. When compared to other algorithms, previously used for classification of CSWV and other similar data, our LSTM and FCN-based neural networks achieve higher sensitivity and specificity with the area under the curve values from receiver operating characteristic (ROC) analyses greater than 0.99 for several datasets. Class activation maps were paired with CSWV scans to assist in understanding the decision-making process of the networks, and their ability to utilize this information was examined. The best-performing models were then successfully applied to new or holdout experimental data. An automated method for processing CSWV data, training machine learning models, and evaluating their prediction performance is described, and the tools generated provide support for the identification of compounds using CSWV from samples in the field.

Acyl carrier protein is a bacterial cytoplasmic target of cationic antimicrobial peptide LL-37.

In addition to membrane disruption, the cathelicidin antimicrobial peptide (AMP) LL-37 translocates through the bacterial inner membrane to target intracellular molecules. The present study aims to identify an alternate mechanism and a cytoplasmic target of LL-37 in Francisella. LL-37 binding proteins from Francisella novicida U112 bacterial lysates were precipitated by using biotinylated LL-37 (B-LL-37) and NeutrAvidin-agarose beads. Bound proteins were identified by LC-MS/MS, validated and characterized by bead pull-down assays and differential scanning fluorimetry (DSF). The cationic AMP (CAMP) LL-37 was able to interact with Francisella cytoplasmic acyl carrier protein (AcpP; FTN1340/FTT1376). Further study confirmed that LL-37 peptide could bind to AcpP and that the sheep cathelicidin SMAP-29 (Sheep Myeloid Antimicrobial Peptide 29) further increased LL-37 binding to AcpP, suggesting a synergistic effect of SMAP-29 on the binding. LL-37 could also bind to both AcpP of Escherichia coli and Bacillus anthracis, implying a mechanism of broad action of LL-37-AcpP binding. Overexpression of the acpP gene in F. novicida led to an increase in LL-37 susceptibility. LL-37 binding to AcpP changed the fatty acid composition profiles. Taken together, we identified a novel cytoplasmic target of LL-37 in Francisella, suggesting a mechanism of action of this peptide beyond membrane permeabilization. Our findings highlight a novel mechanism of antimicrobial activity of this peptide and document a previously unexplored target of α-helical CAMPs.

Burkholderia Diffusible Signal Factor Signals to Francisella novicida To Disperse Biofilm and Increase Siderophore Production.

In many bacteria, the ability to modulate biofilm production relies on specific signaling molecules that are either self-produced or made by neighboring microbes within the ecological niche. We analyzed the potential interspecies signaling effect of the Burkholderia diffusible signal factor (BDSF) on Francisella novicida, a model organism for Francisella tularensis, and demonstrated that BDSF both inhibits the formation and causes the dispersion of Francisella biofilm. Specificity was demonstrated for the cis versus the trans form of BDSF. Using transcriptome sequencing, quantitative reverse transcription-PCR, and activity assays, we found that BDSF altered the expression of many F. novicida genes, including genes involved in biofilm formation, such as chitinases. Using a chitinase inhibitor, the antibiofilm activity of BDSF was also shown to be chitinase dependent. In addition, BDSF caused an increase in RelA expression and increased levels of (p)ppGpp, leading to decreased biofilm production. These results support our observation that exposure of F. novicida to BDSF causes biofilm dispersal. Furthermore, BDSF upregulated the genes involved in iron acquisition (figABCD), increasing siderophore production. Thus, this study provides evidence for a potential role and mechanism of diffusible signal factor (DSF) signaling in the genus Francisella and suggests the possibility of interspecies signaling between Francisella and other bacteria. Overall, this study suggests that in response to the interspecies DSF signal, F. novicida can alter its gene expression and regulate its biofilm formation.

Analysis of mixed biofilm (Staphylococcus aureus and Pseudomonas aeruginosa) by laser ablation electrospray ionization mass spectrometry.

Pseudomonas aeruginosa and Staphylococcus aureus are ubiquitous pathogens often found together in polymicrobial, biofilm-associated infections. This study is the first to use laser ablation electrospray ionization mass spectrometry (LAESI-MS) to rapidly study bacteria within a mixed biofilm. Fast, direct, non-invasive LAESI-MS analysis of biofilm could significantly accelerate biofilm studies and provide previously unavailable information on both biofilm composition and the effects of antibiofilm treatment. LAESI-MS was applied directly to a polymicrobial biofilm and analyzed with respect to whether P. aeruginosa and S. aureus were co-localized or self-segregated within the mixed biofilm. LAESI-MS was also used to analyze ions following LL-37 antimicrobial peptide treatment of the biofilm. This ambient ionization method holds promise for future biofilm studies. The use of this innovative technique has profound implications for the study of biofilms, as LAESI-MS eliminates the need for lengthy and disruptive sample preparation while permitting rapid analysis of unfixed and wet biofilms.

Engineering Outer Membrane Vesicles to Carry Enzymes: Encapsulation, Isolation, Characterization, and Modification.

Outer membrane vesicles (OMVs) are small, spherical, nanoscale proteoliposomes released from Gram-negative bacteria that play an important role in cellular defense, pathogenesis, and signaling, among other functions. The functionality of OMVs can be enhanced by engineering developed for biomedical and biochemical applications. Here, we describe methods for directed packaging of enzymes into bacterial OMVs of E. coli using engineered molecular systems, such as localizing proteins to the inner or outer surface of the vesicle. Additionally, we detail some modification strategies for OMVs such as lyophilization and surfactant conjugation that enable the protection of activity of the packaged enzyme when exposed to non-physiological conditions such as elevated temperature, organic solvents, and repeated freeze/thaw that otherwise lead to a substantial loss in the activity of the free enzyme.

TEMPRO: nanobody melting temperature estimation model using protein embeddings.

Single-domain antibodies (sdAbs) or nanobodies have received widespread attention due to their small size (~ 15 kDa) and diverse applications in bio-derived therapeutics. As many modern biotechnology breakthroughs are applied to antibody engineering and design, nanobody thermostability or melting temperature (Tm) is crucial for their successful utilization. In this study, we present TEMPRO which is a predictive modeling approach for estimating the Tm of nanobodies using computational methods. Our methodology integrates various nanobody biophysical features to include Evolutionary Scale Modeling (ESM) embeddings, NetSurfP3 structural predictions, pLDDT scores per sdAb region from AlphaFold2, and each sequence's physicochemical characteristics. This approach is validated with our combined dataset containing 567 unique sequences with corresponding experimental Tm values from a manually curated internal data and a recently published nanobody database, NbThermo. Our results indicate the efficacy of protein embeddings in reliably predicting the Tm of sdAbs with mean absolute error (MAE) of 4.03 °C and root mean squared error (RMSE) of 5.66 °C, thus offering a valuable tool for the optimization of nanobodies for various biomedical and therapeutic applications. Moreover, we have validated the models' performance using experimentally determined Tms from nanobodies not found in NbThermo. This predictive model not only enhances nanobody thermostability prediction, but also provides a useful perspective of using embeddings as a tool for facilitating a broader applicability of downstream protein analyses.

Multienzymatic Cascades and Nanomaterial Scaffolding-A Potential Way Forward for the Efficient Biosynthesis of Novel Chemical Products.

Synthetic biology is touted as the next industrial revolution as it promises access to greener biocatalytic syntheses to replace many industrial organic chemistries. Here, it is shown to what synthetic biology can offer in the form of multienzyme cascades for the synthesis of the most basic of new materials-chemicals, including especially designer chemical products and their analogs. Since achieving this is predicated on dramatically expanding the chemical space that enzymes access, such chemistry will probably be undertaken in cell-free or minimalist formats to overcome the inherent toxicity of non-natural substrates to living cells. Laying out relevant aspects that need to be considered in the design of multi-enzymatic cascades for these purposes is begun. Representative multienzymatic cascades are critically reviewed, which have been specifically developed for the synthesis of compounds that have either been made only by traditional organic synthesis along with those cascades utilized for novel compound syntheses. Lastly, an overview of strategies that look toward exploiting bio/nanomaterials for accessing channeling and other nanoscale materials phenomena in vitro to direct novel enzymatic biosynthesis and improve catalytic efficiency is provided. Finally, a perspective on what is needed for this field to develop in the short and long term is presented.

Characterization and performance of short cationic antimicrobial peptide isomers.

Cationic antimicrobial peptides (CAMPs) represent an ancient defense mechanism against invading bacteria, with peptides such as the cathelicidins being essential elements of vertebrate innate immunity. CAMPs are typically associated with broad-spectrum antimicrobial potency and limited bacterial resistance. The cathelicidin identified from the elapid snake Naja atra (NA-CATH) contains a semi-conserved repeated 11-residue motif (ATRA motif) with a sequence pattern consistent with formation of an amphipathic helical conformation. Short peptide amides (ATRA-1, -1A, -1P, and -2) generated based on the pair of ATRA motifs in NA-CATH exhibited varied antimicrobial potencies. The small size of the ATRA peptides, coupled with their varied antimicrobial performances, make them interesting models to study the impact various physico-chemical properties have on antimicrobial performance in helical CAMPs. Accordingly, the D- and L-enantiomers of the peptide ATRA-1A, which in earlier studies had shown both good antimicrobial performance and strong helical character, were investigated in order to assess the impact peptide stereochemistry has on antimicrobial performance and interaction with chiral membranes. The ATRA-1A isomers exhibit varied potencies against four bacterial strains, and their conformational properties in the presence of mixed zwitterionic/anionic liposomes are influenced by anionic lipid content. These studies reveal subtle differences in the properties of the peptide isomers. Differences are also seen in the abilities of the ATRA-1A isomers to induce liposome fusion/aggregation, bilayer rearrangement and lysing through turbidity studies and fluorescence microscopy. The similarities and differences in the properties of the ATRA-1A isomers could aid in efforts to develop D-peptide-based therapeutics using high-performing L-peptides as templates.

Bacterial Membrane Vesicles for In Vitro Catalysis.

The use of biological systems in manufacturing and medical applications has seen a dramatic rise in recent years as scientists and engineers have gained a greater understanding of both the strengths and limitations of biological systems. Biomanufacturing, or the use of biology for the production of biomolecules, chemical precursors, and others, is one particular area on the rise as enzymatic systems have been shown to be highly advantageous in limiting the need for harsh chemical processes and the formation of toxic products. Unfortunately, biological production of some products can be limited due to their toxic nature or reduced reaction efficiency due to competing metabolic pathways. In nature, microbes often secrete enzymes directly into the environment or encapsulate them within membrane vesicles to allow catalysis to occur outside the cell for the purpose of environmental conditioning, nutrient acquisition, or community interactions. Of particular interest to biotechnology applications, researchers have shown that membrane vesicle encapsulation often confers improved stability, solvent tolerance, and other benefits that are highly conducive to industrial manufacturing practices. While still an emerging field, this review will provide an introduction to biocatalysis and bacterial membrane vesicles, highlight the use of vesicles in catalytic processes in nature, describe successes of engineering vesicle/enzyme systems for biocatalysis, and end with a perspective on future directions, using selected examples to illustrate these systems' potential as an enabling tool for biotechnology and biomanufacturing.

Computationally Designed AMPs with Antibacterial and Antibiofilm Activity against MDR Acinetobacter baumannii.

The discovery of new antimicrobials is necessary to combat multidrug-resistant (MDR) bacteria, especially those that infect wounds and form prodigious biofilms, such as Acinetobacter baumannii. Antimicrobial peptides (AMPs) are a promising class of new therapeutics against drug-resistant bacteria, including gram-negatives. Here, we utilized a computational AMP design strategy combining database filtering technology plus positional analysis to design a series of novel peptides, named HRZN, designed to be active against A. baumannii. All of the HRZN peptides we synthesized exhibited antimicrobial activity against three MDR A. baumannii strains with HRZN-15 being the most active (MIC 4 µg/mL). This peptide also inhibited and eradicated biofilm of A. baumannii strain AB5075 at 8 and 16 µg/mL, which is highly effective. HRZN-15 permeabilized and depolarized the membrane of AB5075 rapidly, as demonstrated by the killing kinetics. HRZN 13 and 14 peptides had little to no hemolysis activity against human red blood cells, whereas HRZN-15, -16, and -17 peptides demonstrated more significant hemolytic activity. HRZN-15 also demonstrated toxicity to waxworms. Further modification of HRZN-15 could result in a new peptide with an improved toxicity profile. Overall, we successfully designed a set of new AMPs that demonstrated activity against MDR A. baumannii using a computational approach.

Thirty-Day Perioperative Clinical Outcomes of Transcarotid Artery Revascularization vs Carotid Endarterectomy in a Single-Center Experience.

BACKGROUND: Transcarotid artery revascularization (TCAR) has been proposed as a alternative to carotid endarterectomy (CEA) and transfemoral carotid artery stenting in high-risk patients. Recently Centers for Medicare and Medicaid Services expanded coverage for TCAR to include standard surgical risk patients within the Society of Vascular Surgery Vascular Quality Initiative TCAR Surveillance Project. Few single centers compared the clinical outcome of TCAR with CEA. This study compares 30-day perioperative clinical outcomes between TCAR and CEA. STUDY DESIGN: This is retrospective analysis of prospectively collected data from the TCAR Surveillance Project of TCAR patients enrolled in our institution and compared with CEAs done in the same time/with the same providers. The primary outcome was stroke and/or death. Secondary outcomes included stroke, death, MI, cranial nerve injury, bleeding, and others. Propensity matching was done to analyze outcomes. RESULTS: The study analyzed 501 patients (347 CEA, 154 TCAR). There were no significant differences in symptomatic status (43% for CEA vs 38% for TCAR, p = 0.303). TCAR had more patients with hypertension (p = 0.04), coronary artery disease (p = 0.028), and congestive heart failure (p = 0.039). The 30-day perioperative complication rates for CEA vs TCAR were as follows: stroke 1% vs 3% (p = 0.142), stroke/death 1% vs 3% (p = 0.185), MI 0.6% vs 0.7% (p = 1), death 0.6% vs 0% (p = 1), stroke/death/MI 2% vs 4% (p = 0.233), cranial nerve injury 4% vs 2% (p = 0.412), and major hematoma (requiring reintervention) 2% vs 3% (p = 1). After matching 154 CEA patients and 154 TCAR, 30-day perioperative complication rates were as follows: stroke 2% vs 3% (p = 0.723), stroke/death 3% vs 3% (p = 1), death 1.3% vs 0% (p = 0.498), MI 0.7% vs 0.7% (p = 1), and stroke/death/MI 3% vs 4% (p = 0.759). CONCLUSIONS: This study showed that using propensity match analysis, both CEA and TCAR have similar 30-day perioperative outcomes. Further long-term data are needed.

Different Strategies Affect Enzyme Packaging into Bacterial Outer Membrane Vesicles.

All Gram-negative bacteria are believed to produce outer membrane vesicles (OMVs), proteoliposomes shed from the outermost membrane. We previously separately engineered E. coli to produce and package two organophosphate (OP) hydrolyzing enzymes, phosphotriesterase (PTE) and diisopropylfluorophosphatase (DFPase), into secreted OMVs. From this work, we realized a need to thoroughly compare multiple packaging strategies to elicit design rules for this process, focused on (1) membrane anchors or periplasm-directing proteins (herein "anchors/directors") and (2) the linkers connecting these to the cargo enzyme; both may affect enzyme cargo activity. Herein, we assessed six anchors/directors to load PTE and DFPase into OMVs: four membrane anchors, namely, lipopeptide Lpp', SlyB, SLP, and OmpA, and two periplasm-directing proteins, namely, maltose-binding protein (MBP) and BtuF. To test the effect of linker length and rigidity, four different linkers were compared using the anchor Lpp'. Our results showed that PTE and DFPase were packaged with most anchors/directors to different degrees. For the Lpp' anchor, increased packaging and activity corresponded to increased linker length. Our findings demonstrate that the selection of anchors/directors and linkers can greatly influence the packaging and bioactivity of enzymes loaded into OMVs, and these findings have the potential to be utilized for packaging other enzymes into OMVs.

Extracellular vesicle production in Gram-positive bacteria.

This is a highlight on the article 'Extracellular vesicle formation in Lactococcus lactis is stimulated by prophage-encoded holin-lysin system' by Yue Liu, Eddy Smid and Tjakko Abee.

Packaging of Diisopropyl Fluorophosphatase (DFPase) in Bacterial Outer Membrane Vesicles Protects Its Activity at Extreme Temperature.

Enzymatic decontamination of organophosphate compounds offers a biofriendly pathway to the neutralization of highly dangerous compounds. Environmental dissemination of enzymes, however, is an ongoing problem considering the costly process of production and chemical modification for stability that can diminish catalytic activity. As a result, there is interest in the potential for enzymatic encapsulation in situ or into nascent bacterial membrane vesicles to improve catalytic stability across various environmental challenges associated with storage and field deployment. In this study, we have engineered bacterial outer membrane vesicles (OMVs) to encapsulate the diisopropyl fluorophosphatase (DFPase), an enzyme originally isolated from squid Loligo vulgaris and capable of hydrolyzing diisopropyl fluorophosphate (DFP) and other organophosphates compounds. Here we employed a recombinant lipopeptide anchor to direct recruitment of DFPase into OMVs, which were isolated from culture media and tested for catalytic activity against both diisopropyl fluorophosphate and paraoxon. Our encapsulation strategy prevented the loss of catalytic activity despite lyophilization, extended storage time (2 days), and extreme temperatures up to 80 °C. These data underscore the appeal of DFPase as a biodecontaminant of organophosphates as well as the potential for OMV packaging in stabilized field deployment applications.

Natural and synthetic cathelicidin peptides with anti-microbial and anti-biofilm activity against Staphylococcus aureus.

BACKGROUND: Chronic, infected wounds typically contain multiple genera of bacteria, including Staphylococcus aureus, many of which are strong biofilm formers. Bacterial biofilms are thought to be a direct impediment to wound healing. New therapies that focus on a biofilm approach may improve the recovery and healing rate for infected wounds. In this study, cathelicidins and related short, synthetic peptides were tested for their anti-microbial effectiveness as well as their ability to inhibit the ability of S. aureus to form biofilms. RESULTS: The helical human cathelicidin LL-37 was tested against S. aureus, and was found to exhibit effective anti-microbial, anti-attachment as well as anti-biofilm activity at concentrations in the low µg/ml range. The effect of peptide chirality and associated protease-resistance was explored through the use of an all-D amino acid peptide, D-LL-37, and in turn compared to scrambled LL-37. Helical cathelicidins have been identified in other animals such as the Chinese cobra, Naja atra (NA-CATH). We previously identified an 11-residue imperfectly repeated pattern (ATRA motif) within the sequence of NA-CATH. A series of short peptides (ATRA-1, -2, -1A), as well as a synthetic peptide, NA-CATH:ATRA1-ATRA1, were designed to explore the significance of the conserved residues within the ATRA motif for anti-microbial activity. The CD spectrum of NA-CATH and NA-CATH:ATRA1-ATRA1 revealed the structural properties of these peptides and suggested that helicity may factor into their anti-microbial and anti-biofilm activities. CONCLUSIONS: The NA-CATH:ATRA1-ATRA1 peptide inhibits the production of biofilm by S. aureus in the presence of salt, exhibiting anti-biofilm activity at lower peptide concentrations than NA-CATH, LL-37 and D-LL-37; and demonstrates low cytoxicity against host cells but does not affect bacterial attachment. The peptides utilized in this anti-biofilm approach may provide templates for a new group of anti-microbials and potential future topical therapeutics for treating chronic wound infections.

Isolation and Characterization of Membrane Vesicles from Lactobacillus Species.

Throughout their life cycle, bacteria shed portions of their outermost membrane comprised of proteins, lipids, and a diversity of other biomolecules. These biological nanoparticles have been shown to have a range of highly diverse biological activities, including pathogenesis, community regulation, and cellular defense (among others). In recent publications, we have isolated and characterized membrane vesicles (MVs) from several species of Lactobacilli, microbes classified as commensals within the human gut microbiome ( Dean et al., 2019 and 2020). With increasing scientific understanding of host-microbe interactions, the gut-brain axis, and tailored probiotics for therapeutic or performance increasing applications, the protocols described herein will be useful to researchers developing new strategies for gut community engineering or the targeted delivery of bio-active molecules. Graphic abstract: Figure 1. Atomic force microscopic image of Lactobacillus casei ATCC 393 bacteria margins (white arrows) and membrane vesicles (black arrows).